Buy two colors of cotton quilting fabric. For a single block, you need less than 1/4 yard length of fabric. Many fabric stores sell fabric in "fat quarters," which would supply enough fabric for several blocks.
Cut a 4-inch by 4-inch square out of cardboard to use as a template. Using your template as a pattern, cut 5 squares of one color of fabric (fabric "A"), and 4 of the other (fabric "B").
Sew the squares together into three rows with the pattern described above. Lay the first piece of row one face up and the second piece face-down on top of the first piece. Sew ½ inch from the edge along one side.
Lift the second piece and fold it open, so that both pieces are now face-up and use an iron to press the pieces open flat. Continue this method with the right edges aligned, and sew 1/2 inch from the right edge. Repeat to complete rows two and three.
Lay row one down, face up. Place row two face-down on top of row one. Sew 1/2 inch from the bottom, and then pull row two down so that both rows face up. Use an iron to press the rows flat. Repeat for row three.
Complete more nine-patch blocks. In half your blocks, reverse the colors of the squares. To sew the blocks together into a quilt, complete nine, twelve or sixteen blocks. Arrange them in a rectangular pattern.
Sew your nine-patch blocks into rows and sew the rows together to complete a quilt face.